diff --git a/src/triacontagon/split.py b/src/triacontagon/split.py
index 68826f1..77f5eaf 100644
--- a/src/triacontagon/split.py
+++ b/src/triacontagon/split.py
@@ -7,6 +7,10 @@ import torch
 
 
 def split_adj_mat(adj_mat: torch.Tensor, ratios: List[float]):
+    ratios = list(ratios)
+    if sum(ratios) != 1:
+        raise ValueError('Sum of ratios must be 1')
+
     indices = adj_mat.indices()
     values = adj_mat.values()
 
@@ -33,6 +37,10 @@ def split_adj_mat(adj_mat: torch.Tensor, ratios: List[float]):
 
 
 def split_edge_type(et: EdgeType, ratios: Tuple[float, float, float]):
+    ratios = list(ratios)
+    if sum(ratios) != 1:
+        raise ValueError('Sum of ratios must be 1')
+        
     res = [ split_adj_mat(adj_mat, ratios) \
         for adj_mat in et.adjacency_matrices ]
 
diff --git a/tests/triacontagon/test_split.py b/tests/triacontagon/test_split.py
index 2cfc8e7..85ddc9d 100644
--- a/tests/triacontagon/test_split.py
+++ b/tests/triacontagon/test_split.py
@@ -1,5 +1,7 @@
-from triacontagon.split import split_adj_mat
+from triacontagon.split import split_adj_mat, \
+    split_edge_type
 from triacontagon.util import _equal
+from triacontagon.data import EdgeType
 import torch
 
 
@@ -39,3 +41,84 @@ def test_split_adj_mat_03():
     print('a:', a.to_dense(), 'b:', b.to_dense(), 'c:', c.to_dense())
 
     assert torch.all(_equal(a+b+c, adj_mat))
+
+
+def test_split_edge_type_01():
+    et = EdgeType('Dummy', 0, 1, [
+        torch.tensor([
+            [0, 1, 0, 0, 0],
+            [0, 0, 1, 0, 1],
+            [1, 0, 0, 0, 1],
+            [0, 1, 0, 1, 0]
+        ]).to_sparse()
+    ], None, None)
+
+    res = split_edge_type(et, (1.,))
+
+    assert torch.all(_equal(et.adjacency_matrices[0],
+        res[0].adjacency_matrices[0]))
+
+
+def test_split_edge_type_02():
+    et = EdgeType('Dummy', 0, 1, [
+        torch.tensor([
+            [0, 1, 0, 0, 0],
+            [0, 0, 1, 0, 1],
+            [1, 0, 0, 0, 1],
+            [0, 1, 0, 1, 0]
+        ]).to_sparse()
+    ], None, None)
+
+    res = split_edge_type(et, (.5, .5))
+
+    assert torch.all(_equal(et.adjacency_matrices[0],
+        res[0].adjacency_matrices[0] + \
+        res[1].adjacency_matrices[0]))
+
+
+def test_split_edge_type_03():
+    et = EdgeType('Dummy', 0, 1, [
+        torch.tensor([
+            [0, 1, 0, 0, 0],
+            [0, 0, 1, 0, 1],
+            [1, 0, 0, 0, 1],
+            [0, 1, 0, 1, 0]
+        ]).to_sparse()
+    ], None, None)
+
+    res = split_edge_type(et, (.4, .4, .2))
+
+    assert torch.all(_equal(et.adjacency_matrices[0],
+        res[0].adjacency_matrices[0] + \
+        res[1].adjacency_matrices[0] + \
+        res[2].adjacency_matrices[0]))
+
+
+def test_split_edge_type_04():
+    et = EdgeType('Dummy', 0, 1, [
+        torch.tensor([
+            [0, 1, 0, 0, 0],
+            [0, 0, 1, 0, 1],
+            [1, 0, 0, 0, 1],
+            [0, 1, 0, 1, 0]
+        ]).to_sparse(),
+
+        torch.tensor([
+            [1, 0, 0, 0, 0],
+            [0, 1, 0, 1, 0],
+            [0, 0, 1, 1, 0],
+            [1, 0, 1, 0, 0]
+        ]).to_sparse()
+    ], None, None)
+
+    res = split_edge_type(et, (.4, .4, .2))
+
+    assert torch.all(_equal(et.adjacency_matrices[0],
+        res[0].adjacency_matrices[0] + \
+        res[1].adjacency_matrices[0] + \
+        res[2].adjacency_matrices[0]))
+
+    assert torch.all(_equal(et.adjacency_matrices[1],
+        res[0].adjacency_matrices[1] + \
+        res[1].adjacency_matrices[1] + \
+        res[2].adjacency_matrices[1]))